Frequency-dependent Faraday and Kerr rotation in anisotropic nonsymmorphic Dirac semimetals in a magnetic field

We calculate the frequency-dependent longitudinal and Hall conductivities and the Faraday and Kerr rotation angles for a single sheet of anisotropic Dirac semimetal protected by nonsymmorphic symmetry in the presence of a perpendicular magnetic field. While the magnetic field causes a rotation of the plane of polarization of the light, the anisotropy causes the appearance of an elliptically polarized component in an initially linearly polarized beam. The two effects can be combined in a single complex Faraday rotation angle. At the zero-frequency limit, we find a finite value of the Faraday rotation angle, which is given by $2\alpha_F$, where $\alpha_F$ is the effective fine structure constant associated with the velocity of the linearly dispersing Dirac fermions. We also find a logarithmic enhancement of the Faraday (and Kerr) rotation angles as the frequency of the light approaches the absorption edge associated with the magnetic field-induced gap. While the enhancement is reduced by impurity scattering, it remains significant for an attainable level of material purity. These results indicate that two-dimensional Dirac materials protected by nonsymmorphic symmetry are responsive to weak magnetic fields and can be used as platforms for magneto-optic applications, such as the realization of polarization-rotating devices.Comment: 24 pages, 7 Figure

Detection of biomarker in breath: A step towards noninvasive diabetes monitoring

Along with more than two hundred volatile organic compounds (VOCs), acetone is also a normal constituent of breath of healthy individuals, albeit in the sub-ppm range, and its concentration increases in diabetic patients. Considering the importance of breath acetone as a biomarker of diabetes, some studies have already been made to measure breath acetone concentration (and correlate with blood sugar level) using GC-MS. There are a few reports of measuring breath acetone concentration using semiconductor sensor in the background of air (i.e. in the absence of VOCs present in normal breath and hence the question of selectivity remains in the real situation) and at a higher concentration (above 10 ppm). We report excellent sensitivity of sonochemically prepared nanosized gamma-Fe2O3 sensors towards sub-ppm acetone (pathological range) in the background of human breath. Our preliminary results should stimulate further research towards developing cheap, rugged and compact semiconductor sensors for noninvasive monitoring of diabetes

Ligand and solvent effects in the formation and self-assembly of a metallosupramolecular cage

Two bis-pyridyl-bis-urea ligands namely N,N'-bis-(3-pyridyl)diphenylmethylene-bis-urea (L1) and N,N'-bis-(3-picolyl)diphenylmethylene-bis-urea (L2) have been reacted with a Cu(ii) salt resulting in the formation of a metallosupramolecular cage [{Cu(μ-L1)(DMSO)(HO)}·SO·X] (1) and a one-dimensional coordination polymer [{Cu(1)(μ-L2)(HO)}{Cu(2)(μ-L2)(HO)}·2SO·9HO·X] (2) (where DMSO = dimethylsulfoxide, and X = disordered lattice included solvent molecules), respectively. The single crystal structures of 1 and 2 are discussed in the context of the effect of the ligands, particularly the hydrogen bonding functionality of the ligand, on the supramolecular structural diversities observed in these metal organic compounds. The supramolecular packing of 1 is clearly influenced by the nature of the solvent and ligand used; mixtures of DMSO/MeOH or DMSO/HO lead to the formation of blue crystals or a hydrogel, respectively

Carbon-based adsorbents from naturally available Bermuda grasses : removal of TDS and arsenic ions

In the present study, we have reported the synthesis of nano porous carbon material (GC) by the thermal treatment of the commonly available Bermuda grasses, and metal oxides doped bio-compatible polymer chitosan-GC based porous cross-linked composites (CHGCCZ) as adsorbent materials for the removal of total dissolved solids (TDS) and efficient removal of arsenic (As(V)) ions from aqueous medium, respectively. The synthesized adsorbents have been characterized by FTIR, PXRD, FESEM, TGA, and the systematic investigations have shown that the incorporation of GCs into cross-linked matrix makes them porous, more resistant to degradation, and suitable adsorption matrix for the toxic As(V) removal. The presence of As(V) ions is quantified by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) measurements. The amount of TDS and arsenic concentration was reduced to the minimum value of 103 ppm (average value∼119 ppm) from 414 ppm and 7.7 ppm from very high concentration of 10.15 ppm, respectively. The recyclability test has also been performed after regeneration of the CHGCCZ and the initial findings has been found to be promising. Therefore, we have systematically investigated the efficacy of TDS removal by GCs and As(V) adsorption properties of metal oxide doped cross-linked CHGCCZ composite from the aqueous system and demonstrated the regeneration process for CHGCCZ in our study

Complex plane impedance plot as a figure of merit for tin dioxide-based methane sensors

Thick film methane sensors have been fabricated from nanosized tin dioxide powder containing antimony oxide and palladium. The powder has been prepared by sonication-assisted simultaneous precipitation and the sensors made with this powder showed optimum resistance for device applications and good sensitivity towards methane. This contrasts with the thick film sensors prepared with the powder synthesized without sonication, which showed very high resistance at the operating temperature. The complex plane impedance spectroscopy of the sensors (both in air and in the presence of gas) can be a good indicator of the sensor quality. It has been observed that the nature of the complex plane impedance plot of the sensors fabricated by using powders synthesized through sonication-assisted simultaneous precipitation matches well with that of high-quality imported Figaro (Japan) sensors

Selective detection of methane and butane by temperature modulation in iron doped tin oxide sensors

In the present study we find that it is possible to develop sensors based on iron doped tin dioxide, which can detect both methane and butane (present in CNG and LPG, respectively) at a temperature of 350 °C. However, the same sensors can selectively detect butane at a temperature of 425 °C. Such differential behaviour can be explained by considering the decrease in the number and/or strength of Lewis acid sites on SnO2 due to Fe-doping and the role of chain length on the adsorption–desorption characteristics of alkanes. However, the incorporation of palladium as a catalyst in Fe-doped SnO2 sensors removes the typical selectivity, and the temperatures of the maximum response coincide for methane and butane

Label-Free Cysteamine-Capped Silver Nanoparticle-Based Colorimetric Assay for Hg(II) Detection in Water with Subnanomolar Exactitude

Precisely probing heavy metal pollutants in water warrants novel methods and materials. To this end, functionalization of nanoparticles using biologically important substances through a green route is a novel aspect in the design of an optical sensor. In this article we report a green preparative strategy for the synthesis of cysteamine stabilized silver nanoparticles (Ag-Nps) in aqueous medium. The water-soluble Ag-Nps are found to be highly sensitive and selective for rapid colorimetric detection of Hg­(II) ion with a limit of detection (LOD) of 0.273 nM (55 ppt). This system also enables us to detect Hg­(II) through the naked eye with an LOD of 2.73 nM (0.55 ppb) which is below the World Health Organization (WHO) permissible limit (10 nM or 2 ppb). Cysteamine undergoes cooperative coordination with the mercury ion leading to spontaneous formation of a mercury–cysteamine complex and consequently forms Ag–Hg nanoalloy, which in turn changes the surface plasmon property of Ag-Nps to allow detection of Hg­(II) ion with subnanomolar precision. Furthermore, Ag-Nps were tested for detection of Hg­(II) in different real water samples with satisfying recoveries over 96–102%

Room temperature synthesis of nanocrystalline SnO through sonochemical route

Nanocrystalline tin monoxide (SnO) has been synthesized through sonication-assisted precipitation technique at room temperature. The key in obtaining phase pure SnO at room temperature lies in exploiting high-power ultrasound (450W). The physical phenomenon responsible for the sonochemical process is acoustic cavitation. A mixed phase is formed on decreasing the ultrasonic power.-The heat generated during sonication does not explain the difference in phase formation under varying ultrasonic power as the difference in temperatures of the solutions during sonication under different power ratings was within 10-15 degrees C. SEM and XRD analysis were carried out for the investigation of powder morphology and crystalline structure of the material. (C) 2007 Published by Elsevier B.V

An extension of cancer immunotherapy with dostarlimab, the PD1-PD L1 pathway blocker

Cancer immunotherapy is a treatment that uses the body's own immune system to fight against cancer. Malignant cells in the human body have the ability to mutate themselves in such a way that they can escape from immune system surveillance and proliferate. So, if the human immune system could be boosted or its surveillance and defensive mechanisms improved so that our bodies can detect cancer cells and kill them by combining all of the human body's defensive mechanisms, it would be much easier to deal with cancer. A recent trial at Memorial Sloan Kettering Cancer Center in New York found that by using a drug called Dostarlimab, rectal adenocarcinoma could be cured by boosting the human immune system to detect and kill cancer cells. This could be considered a validated extension of cancer immunotherapy. This paper will explain how dostarlimab works on the body's immune system and destroys cancer cells in a simple way that anyone who is not in the medical field also can understand

A new synthetic route to Lindqvist type clusters [(n-Bu₄N)x][M′M₅O₁₉] [when x = 2, M′ = M = Mo or W; x = 3, M′ = Mo, M = W] from metal carbonyl precursors [(CO)₅ML] [M = Mo, W; L= CO, C(OMe)(Me)]

Two fully oxidized [(n-Bu4N)2][Mo6O19], 7 and [(n-Bu4N)2][W6O19], 8 and one mixed-metal, mixed-valence one electron reduced [(n-Bu4N)3][MoW5O19], 9 cluster have been synthesized under biphasic reaction conditions from group VI metal carbonyls or Fischer carbene complexes, [(CO)5M[double bond, length as m-dash]C(OMe)Me] (M = Mo, W) in yields of 73, 77 and 71% respectively. All the clusters have been characterized by IR, 1H and 13C NMR spectra, and crystal structure determinations. Additionally, the composition of 9 has also been supported by mass spectrometry (MALDI-TOF), inductively coupled plasma (ICP) and energy-dispersive X-ray (EDX) analysis. This novel and mild route offers distinct improvements over earlier methods of synthesis for Lindqvist type mixed-valence mixed-metal polyoxometalate cluster